Romney put gentle but unmistakable distance between his agenda and Ryan's hot-potato budget proposals on Sunday as the new team soaked up excitement from partisans in North Carolina and Ryan's home state of Wisconsin.

He walked a careful line as he campaigned with Ryan by his side in North Carolina, singling out his running mate's work "to make sure we can save Medicare." But the presidential candidate never said whether he embraced Ryan's austere plan himself, and he addressed the matter more directly in a "60 Minutes" interview, with Ryan still with him, on Sunday night.

"He is a decent man, he is a family man, he is an articulate spokesman for Gov. Romney's vision — but it is a vision that I fundamentally disagree with," Obama said in his first public comments about Ryan's selection.

During the Republican primary, Romney had called Ryan's budget a "bold and exciting effort" that was "very much needed."

Ryan proposed to reshape the long-standing entitlement by setting up a voucher-like system to let future retirees shop for private health coverage or choose the traditional program — a plan that independent budget analysts say would probably mean smaller increases in benefits than current law would provide.

Romney and Ryan, in their first joint television interview Sunday, were clearly mindful that some of Ryan's proposals don't sit well with key constituencies, among them seniors in critical states like Florida and Ohio. Each man sought to reassure older voters they wouldn't take away their benefits, with Ryan saying his mother is "a Medicare senior in Florida" and Romney vowing there would be "no changes" for seniors currently counting on the popular federal program.

"In America, the nature of this country has been giving people more freedom, more choices," Romney said. "That's how we make Medicare work down the road."

Romney praised his running mate for his policy depth and analytical skills and said if they should win the election, Ryan will surely be consulted in big decisions — "along with other individuals." He added: "Obviously I have to make the final call in important decisions."

The presumptive presidential nominee said Ryan "if it were necessary, could become president." And Romney extolled his running mate's Washington experience, despite having criticized primary rivals Newt Gingrich and Rick Santorum for their years in the nation's capital.

Ryan said he planned to release two years of personal tax returns to the public. The wealthy Romney also is releasing two years of returns, despite pressure from Democrats and some Republicans to provide more information about how he manages his millions.

Romney, seeking to pull his campaign out of a summer slump, appeared to relish campaigning alongside the youthful and energetic Ryan.

"This is Day Two for me," a gleeful Romney told a campaign rally in Mooresville, N.C. "This is Day Two on our comeback tour to get America strong again, to rebuild the promise of America." He meant a comeback for the country, but that could apply as well to his campaign.

The duo blitzed through North Carolina — a competitive battleground state in the November election — as part of a multistate bus tour. The pair ended the day in Waukesha, Wis., with a homecoming-themed event for Ryan, who was in tears as he took the stage.

Romney, emboldened by the enthusiastic crowds that greeted the pair Sunday, wrapped up a day of campaigning with a sharp shot at Obama. "Mr. President, take your campaign out of the gutter," he said.

Romney then planned to head to Florida and Ohio as the week begins, while Ryan was scheduled to travel to Iowa on Monday.

For Ryan, the weekend of campaigning was a chance to make a first impression on many voters. A recent CNN/ORC international poll found a majority of voters had no opinion of the congressman: Nearly 40 percent had never heard of him and 16 percent weren't sure what they thought of him.

The 42-year-old congressman embraced the attack dog role traditionally assumed by the No. 2 on the ticket. He said Obama had turned his 2008 campaign slogan of "hope and change" into "attack and blame."

"We're not going to fall for it," Ryan told a crowd of 5,000 in High Point, N.C.

Republicans say Ryan could help put Wisconsin, which traditionally has voted Democratic in presidential campaigns, in play and that the Catholic Midwesterner also could appeal to blue-collar voters whom Romney has struggled to reach in Iowa and elsewhere.

Obama's campaign, however, had no plans to start running new television ads in Wisconsin following Ryan's pick. Officials said they didn't think Ryan was popular enough statewide to swing Wisconsin toward the Republican ticket.